Production of isoprene.



UNITED STATES PATENT onmcn.

' HEINEHAN'N, OF SOUTH KENSINGTON, LONDON, ENGLAND.

PRODUCTION OF ISOPRENE.

80 Drawing.

To' all whom it may concern:

Be it known that I, ARTHUR HEINEMANN, subject of the King of Prussia, residing at 10 Sumner Terrace, ()nslow Square, South Kensington, London, S. W., England, have invented new and useful Improvement-s Relating to the Production of Isoprene, of which the following is a specification.

This invention consists of improvements in the production of isoprene by the depolymerization of turpentine oil.

Sir William Tilden by his researches proved that it was possible to produce isoprene from turpentine oil if the latter was passed through an iron tube heated to a dull red heat. The result obtained was but a very small quantity of isoprene, about. 6.25

per cent. of the turpentine oil used. It has also been proposed to obtain isoprene by passing vapors of turpentine oil through an iron tube heated to a temperature of between 550 C. and 600 C. and filled with rolls of iron, or wire, gauze or perforated disks formed of iron.

The object of my invention is to obtain a greater yield of isoprenethan has hitherto been possible.

According to my invention I use copper, instead of iron, as a catalytic or contact surface. I have found that this metal possesses the important advantage, probably due to its more highly conductive nature, of allowing the isoprene to be produced at a lower temperature than when iron is employed. The copper must either be in a finely divided-state, in which case it would be contained in a tube of iron or other suitable -material, or must form the 'substance'of which is constructed the tube or structure in which the depolymerization'is eifected.

Said tubeor structuremay be of any suitable form. For instance it may consist of a, helical, spiral or zig-zag tube, or of a box provided with aseries of baflle plates so disposed with respect to one another that the vapor of the turpentine oil is'compeHed to travel in a sinuous ath.

In order to obtain the maximum yield of isoprene and prevent the isoprene being converted into dipentene, the depolymeriza- Specification of Letters Patent.

Application filed June 9, 1911. Serial No. 632,202.

Patented May 5, 1914.

tion should be effected at as low a temperature as possible and the rate of flow and length of pipe so,adjusted that polymeriza-' tion of the isoprene is prevented as far as possible. It is advisable to connect the delivery tube to a condenser of suitable size, which is preferably cooled by a freezing mixture.

The invention may be carried out in the following manner :The vapor of turpentine oil is passed through or over the heated copper at the lowest temperature which is found to work satisfactorily. This temperature, if there is ample surface exposed to the vapor, is about 480 C. Good results may be obtained if a tube of 6 mm. internal diameter and 4 meters in length is closely wound into a coil and the rate offlow of the vapor through said coil is regulated so as to be equal to or approximately equal to 2,000 0. cm. per hour. As a result of the depolymerization of the turpentine oil isoprene and a number of other hydrocarbons are produced, equal to about fifty per cent. by volume of the quantity of the turpentine vapor. The isoprene, whichcan be readily separated from .other hydrocarbons by distillation, will be found to be about twenty-five per cent. of the original volume of turpentine oil.

Having now described my invention what I have invented and desire to secure by Letters Patent of the United States is as follows I 1. A process for the production of isoprene from turpentine oil consisting in pass-.

ing the vapors of turpentine oil over heated copper, substantially as described.

2. A process for the production of isoprene from turpentine oil consisting in passthe vapors of turpentine oil through a heated structure of suitable form constructed of copper, substantially as described;

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ARTHUR HEINEMANN.

Witnesses:

F. ENNIS, .H. D. Jansen. 

